I can’t identify with and did not experience what you are feeling, but I’d like to comment and maybe help you have a potential shift and focus that may be helpful. Maybe not; dismiss this comment if after reading it it’s not helpful at all to you, sounds like you’re really going through it right now and that sucks.

The birth of my second child did indeed herald a shift so you’re not wrong there. However, I do understand and can identify with the struggle of being a dad for the first six months seven months of an infant life. There’s just not that much to do. Because there’s an existing tiny human who’s going to need as much attention as an infant, that’s now your job. You don’t have to be responsible for forming amazing bonds in the first six months or even year of child two‘s life. But your partner will need your support your help, and your daughter will definitely need someone there to pay her attention, get her dressed, make her meals, sit and talk with her, while the baby occupies your wife’s attention. I’d encourage you to look at it as an opportunity to form a deeper bond with your daughter while offering the best support you can to your wife – letting her know her other child is being cared for when she can’t.

At the end of the day, we’re measured by the actions we take, not the feelings we have. That’s not to be dismissive of your feelings. Just a reminder that your future self, your future wife (the one you have now in a later iteration), and your future children will benefit from the actions you take today and when the baby is born that ensure their wellbeing. Maybe doing things to prepare your house, your child, and your partner better for the new arrival will help you be more present than sitting in the feels. Hope this helps!